Cholinergic stimulation of the lateral hypothalamic neurons with intrahypothalamic microinjections of acetylcholine or carbachol caused a marked increase in the content of the active form of glycogen (starch) synthase in the liver. Total activity of the enzyme (active plus inactive forms) was not increased significantly. The lowest effective dose of acetylcholine was 5 X 10(-10) mole, and the optimum dose was 5 X 10(-9) mole. Similar applications of other neurotransmitters, such as norepinephrine, dopamine, serotonin, and gamma-aminobutyric acid, did not affect the enzyme's activity.